1. Field of the Invention
The subject invention relates to a thrust bearing assembly as part of an engine assembly for use in a vehicle.
2. Description of the Related Art
Crankshafts are journaled in engine blocks by a series of axially spaced engine bearing assemblies. Each engine bearing assembly includes an upper portion seated in an arcuate recess of the block and an accompanying lower portion clamped tightly against the upper bearing half by a supportive bearing cap bolted to the engine block. At least one of the engine bearings in the set is designed to absorb axial thrust forces imported by the crankshaft during operation. The so-called thrust bearing differs from the other engine bearing in that it has two axially spaced thrust flanges that project radially outwardly. The thrust bearing presents opposite axially outwardly directed thrust faces which are seated on their backsides against the support surfaces of the block and engage associated thrust surfaces of the crankshaft, when necessary, to provide the thrust support. These thrust flanges typically have a uniform thickness and often are formed with oil grooves and contours to impart a hydrodynamic oil film action to the bearing.
During operation of the engine, loads on the crankshaft tend to force the crankshaft in axially opposite directions, accounting for the aforementioned thrust loads imparted to the thrust flanges of the thrust bearing. As the thrust loads are applied in one axial direction, it will be appreciated that the forward-most set of upper and lower thrust flanges will be confronted by the crankshaft thrust surface and will be seated tightly against the associated support surface of the block. It will be further appreciated that when a thrust force is applied by the crankshaft in the axially opposite direction that the opposite set of thrust flanges will be tightly seated against their associated support surfaces of the block. This constant force has the detrimental effect of stressing the thrust bearing of the base of the thrust flanges, which can lead to premature failure of the thrust bearing.
Most related art assemblies have hydrodynamic features on all thrust flanges or at least on three of the thrust flanges with two flanges having hydrodynamic features axially aligned. One such related art assembly is illustrated in FIGS. 6 and 7. FIG. 6 is a bottom perspective view of a thrust bearing assembly 100 having a thrust bearing 102 with one flange 104 having hydrodynamic features 106 and one flange 108 free of hydrodynamic features, a main bearing 110, and a thrust washer 112 having hydrodynamic features 114. The assembly 100 has an orientation device 116 that requires the assembly 100 to be positioned with the flanges having hydrodynamic features 104, 112 directly opposite one another such that the flanges 104, 112 are axially aligned. FIG. 7 is a cross-sectional view of the thrust bearing assembly 100 of FIG. 6. The two axially aligned flanges 104, 112 having hydrodynamic features absorb the major thrust forces of the engine. However, the axially spaced flange 108 free of hydrodynamic features is subjected to the minor thrust forces. These forces stress the other flange 108 which causes premature failure of the assembly 100.
The related art assemblies are characterized by one or more inadequacies as described above. It is an object of the present invention to reduce the cost of manufacturing the bearing assembly, while also absorbing the thrust forces generated by the engine.